(See Energy Level Diagrams for 6Li)
Shell model: (1961KO1A, 1965CO25, 1966BA26, 1966GA1E, 1966HA18, 1966WI1E, 1967BO1C, 1967CO32, 1967PI1B, 1967WO1B, 1968BO1N, 1968CO13, 1968GO01, 1968LO1C, 1968VA1H, 1969GU10, 1969RA1C, 1969SA1C, 1969VA1C, 1970LA1D, 1970SU13, 1970ZO1A, 1971CO28, 1971JA06, 1971LO03, 1971NO02, 1972LE1L, 1972LO1M, 1972VE07, 1973HA49, 1973JO1K, 1973KU03).
Cluster and α-particle model: (1965NE1B, 1966HA12, 1967AL1D, 1967BA1H, 1967HA1J, 1967LO1E, 1967SI1C, 1967TH02, 1968BA35, 1968HA1G, 1968KU1B, 1968SA1C, 1969AL1E, 1969BE1N, 1969CH40, 1969CL1D, 1969HA1N, 1969HA1P, 1969JA13, 1969KU13, 1969ME1C, 1969NE1C, 1969SM1A, 1969TH1C, 1969TR1B, 1969VE1B, 1970CH1N, 1970FA11, 1970IT02, 1970JA21, 1970KU1F, 1970NE1F, 1971AM1A, 1971AM03, 1971AU01, 1971CH06, 1971HA59, 1971HU1F, 1971KU06, 1971NO02, 1971PA11, 1971ST31, 1972EL04, 1972JA21, 1972KU12, 1972KU20, 1972OS01, 1973KR07, 1973KU03, 1973KU12, 1973MA51, 1973RA23, 1973WE07).
Electromagnetic transitions: (1962MO1A, 1965CO25, 1966BA26, 1966HA12, 1967BA1H, 1968CO13, 1968LE02, 1969BE1N, 1969HA1F, 1969HA1N, 1969LA1D, 1969VA1C, 1970LA1D, 1971LO10, 1971MU19, 1971ST31, 1972NA05, 1973HA49, 1973HA1V, 1974VE02, 1973WE18).
Muon and neutrino interactions: (1965LO1B, 1968DE1L, 1969GA1N, 1969KR1C, 1969KU13, 1969WU1A, 1970DE1M, 1970DE1N, 1970FA15, 1970KI1C, 1971DE2D, 1971ER1C, 1971WI10, 1972MI1M, 1972MU07, 1973BE07, 1973BE51, 1973DO07, 1973MU11, 1974WI1T).
Pion capture and reactions: (1966DA1A, 1966DE1G, 1966KO1C, 1966TA1A, 1967CH1F, 1967KO1C, 1967KO1D, 1967LE1D, 1967ME1F, 1967SA1D, 1968AL1F, 1968BA1X, 1968CH1G, 1968CH1H, 1968DE1L, 1968GR1D, 1968KU1B, 1968NG1A, 1968NO1A, 1968PE1B, 1968WI1B, 1968ZU1A, 1969AL1E, 1969BU1C, 1969CA1B, 1969GO1C, 1969KO30, 1969MI10, 1969MO1E, 1969NE1C, 1970AL1K, 1970BA59, 1970BA1E, 1970CA1L, 1970CH1L, 1970CH1N, 1970DE1N, 1970JA23, 1970KO23, 1970NE1F, 1970PA1E, 1971AM1A, 1971CA1J, 1971FA09, 1971GR1Y, 1971KO02, 1971PA11, 1971WE1J, 1972FA14, 1972HU1A, 1972JA21, 1972ME1F, 1972SA10, 1972SW1A, 1972TR1E, 1972VE07, 1973BA2R, 1973BA2V, 1973BA62, 1973BR1J, 1973CH1V, 1973DO1F, 1973KA1D, 1973MA11, 1973NI1C, 1973NY04, 1973PE1E, 1973VE1F, 1974VE02).
Kaon reactions: (1973BA1Y).
Other topics: (1965BE1F, 1965CO25, 1965LO1C, 1966FL1A, 1966FR1C, 1966HA18, 1966NA1A, 1966WI1E, 1967AL1D, 1967BL1D, 1967BO1C, 1967CA17, 1967FR1A, 1967RI1A, 1967SI1C, 1967WO1B, 1968CI1D, 1968GO01, 1968GO24, 1968KU1C, 1968LE02, 1968LE1F, 1968RI1L, 1968SA1D, 1969AF1A, 1969AL1D, 1969CH40, 1969GU10, 1969IN1A, 1969LA1D, 1969LE1G, 1969RA21, 1969SA1C, 1969SH20, 1969WA1F, 1969YE1A, 1970AL14, 1970FO1B, 1970HA1N, 1970KA1K, 1970KR1H, 1970LO1E, 1970PA1D, 1970SH1B, 1970SU13, 1970WI11, 1970ZO1A, 1971DE1V, 1971HU1F, 1971KU06, 1971WE1K, 1971ZA1D, 1972AB14, 1972AN05, 1972CA37, 1972EL04, 1972GH1A, 1972LE1L, 1972LO1M, 1972NI15, 1972RI10, 1973BA1Y, 1973CH08, 1973CL09, 1973JO1K, 1973KR07, 1973KU03, 1973MA51, 1973MA48, 1973RO1R).
Ground-state properties: (1965CO25, 1966BA26, 1966WI1E, 1967SH05, 1967SH14, 1968GO24, 1968LE02, 1968PE1B, 1969AF1A, 1969CH25, 1969CH40, 1969GU08, 1969JA1H, 1969LA1D, 1969PE1D, 1969TR1B, 1969VA1C, 1970AF02, 1970CH1M, 1970JA21, 1970LA1D, 1971CH06, 1971HA59, 1971ST31, 1972LE1L, 1972LO1M, 1972VA36, 1973DO1F, 1973MA1K, 1973MA51, 1973SU1B, 1974VE02).
Capture γ-rays (reaction (a)) to the first three states of 6Li [γ0, γ1, γ2] have been observed for E(3He) = 0.5 to 20.0 MeV (1968BL10, 1970YO1A), 1 to 3 MeV (1963KO04), 5 to 20 MeV (1966NU01) and 5.4 to 25.8 MeV (1971VE10, 1973VE1B). In addition the yields of γ3, γ4 have been measured for E(3He) = 12.6 to 25.8 MeV (1971VE10, 1973VE1B). The γ2 excitation function does not show resonance structure. However, the γ0, γ1, γ3 and γ4 yields do show broad maxima at E(3He) = 5.0 ± 0.4 [γ0, γ1], 20.6 ± 0.4 [γ1], ≈ 21 [γ3] and 21.8 ± 0.8 [γ4] MeV. The magnitude of the ground state capture cross section is well accounted for by a direct capture model; that for the γ1 capture indicates a non-direct contribution above E(3He) = 10 MeV, interpreted as a resonance due to a state with Ex = 25 ± 1 MeV, Γc.m. = 4 MeV, T = 1 (because the transition is E1, to a T = 0 final state) [the E1 radiative width |M|2 ≳ 5.2/(2J + 1) W.u.], Jπ = (2, 3, 4)-, α + p + n parentage (1973VE09, 1973VE1B). The γ4 resonance is interpreted as being due to a broad state at Ex = 26.6 MeV with T = 0. Jπ = 3- is consistent with the measured angular distribution (1973VE1B). The ground and first excited state reduced widths for 3He + t parentage, θ20 = 0.8 ± 0.2 and θ21 = 0.6 ± 0.3 (1971VE10, 1973VE09, 1973VE1B). (1970YO04) calculate that the upper limit to the t + 3He clustering is θ20 = 0.69, θ21 = 0.55, θ22 = 0.48 for the first states of 6Li.
Elastic scattering (reaction (f)) angular distributions have been measured at E(3He) = 5.00, 7.00, 9.00, 11.00 MeV (1968IV01), 5.8 to 19.9 MeV (1968BA2C) and 27.7 and 32.3 MeV (1970BA29). Excitation functions are reported for E(3He) = 4.48 to 11.94 MeV (1968IV01), 4.3 to 21.4 MeV (1968BA2C) and 24.7 to 33.4 MeV (1970BA29). At the lower energies the elastic yield is structureless and decreases monotonically with energy (1968IV01). Above E(3He) = 15 MeV a marked change in the angular distributions is attributed to a broad resonance in the l = 3 partial wave (1968BA2C) which is reported by (1970BA29) to be located at 6Li*(29.0) [Γ ≈ 4 MeV] (see, however, reaction (a) above): the resonance is tentatively associated with the 1F and 3F levels predicted from the one-channel resonating group theory (1967TH1C, 1968TH01). See also (1968OH04, 1973NO07) and (1972BR1Q, 1972JA1K, 1972KU20; theor.).
Angular distributions and total cross section measurements for reactions (b), (c) and (e) are listed in (1966LA04). Angular distributions of deuterons (reaction (e)) at Et = 1.04 to 1.52 MeV (1970NA1E), Et = 1.51 to 3.27 MeV (1972WA1L) and at E(3He) = 0.29 to 0.80 MeV (1973NO07) are approximately (to within 1%) symmetric about 90°, as expected from isospin conservation: see also reaction 4. On the basis of a composite of available measurements (1973NO07) suggest that two broad resonances occur in the differential cross sections at θc.m. = 10° and 90° corresponding to 6Li states at Ex ≈ 16.2 MeV and ≈ 17 MeV, with Jπ; T possibly 2+; 1 and 1-; 0, respectively. For reaction (e) see also (1968ME03) and (1967BI1C; theor.). Measurements for reaction (c) lead to a n - p scattering length anp = -21 ± 3 fm (1972KU08). See also (1968BL06, 1970BE1N, 1970GR17, 1971BE21, 1972KU1N, 1973RO2A, 1973SL03).
The angular distribution and polarization of the neutrons in reaction (d) has been measured at E(3He) = 2.70 and 3.55 MeV. The excitation function for E(3He) = 0.7 to 3.8 MeV decreases monotonically with energy (1971KL04). The excitation function for the n0 group (θlab = 20°) has been measured for E(3He) = 14 to 26 MeV; evidence for a broad structure at E(3He) = 20.5 ± 0.8 MeV, Γ ≈ 6 MeV is reported [Ex = 26.1 MeV] (1973VE1B, 1974CH15). See also (1969VA1G, 1973GR1L, 1973LI19; theor.).
For reactions (g), (h), (i) and (j) see (1973SL03: E(3He) = 50 MeV): evidence for quasi-free reaction mechanism is observed in reactions (c), (i) and (j) and for d - d, p - 3He and d - 3He quasi-free scattering in reactions (i), (h) and (g), respectively.
For reaction (a) see 5Li, (1966LA04) and (1971NO1C). The proton yield (reaction (b)) gives no evidence of states in 6Li with 6.5 < Ex < 8.7 MeV (1964OH01). Polarization measurements at Ed = 8.5, 10 and 11 MeV (1971KE16) and 11 to 17 MeV (1972AV1E) indicate scattering through the first two states of 5He. The vector analyzing power has been measured at Ed = 32.1 and 41.0 MeV (1973CO2A, 1973DA1Q: detected 3H and 3He).
Studies of the t and 3He differential cross sections (reaction (c)) at Eα = 48.3 MeV (1971WA20) and at Eα = 49.9, 64.3 and 82.1 MeV (1970GR07, 1972GR07) show pronounced deviations from 90°c.m. symmetry which are angle and energy dependent. [See analysis in (1973ED02)]. The observed asymmetries can be accounted for in terms of the p and the n separation energies in 4He (1972GR07). The asymmetry remains but is considerably smaller at Eα = 166 MeV (1973BA2U): it is attributed in part to Coulomb effects. See also (1969HA1Q, 1973FI04) and (1970RI16, 1971KO14, 1971MU17, 1972KN05, 1973BE2H; theor.).
For reactions (d) and (e) see (1972LI04: Ed = 52 MeV).
Elastic scattering differential cross-section measurements have been carried out previously at many energies up to 27.3 MeV: see (1966LA04) for a listing of the previous work. Recently, measurements have been reported at Ed = 2.48 MeV (1964MA50), 3 to 14 MeV (1968MA03), 12.00 MeV (1971JE01), 14.2 MeV (1967FU1D), 27.1 to 39.6 MeV (1969HA1Q) and at Eα = 166 MeV (1969BR19). Polarization measurements are listed in Table 6.3 (in PDF or PS). See also the reviews by (1966DA1B, 1971PL1C), (1972OH02) who set up a convenient parametrization for 1 + 0 → 1' + 0' polarization transfer phenomena, and (1973OH01, 1973OH02).
Phase shift analyses have been carried out for Ed = 0.3 to 4.2 MeV (1955GA74), 2 to 10 MeV (1967MC02), 3 to 10 MeV (1964SE07), 3 to 11 MeV (1970KE17), 3 to 11.5 MeV (1972SC14) and 10 to 27 MeV (1967DA1B). See also (1968MA03). (1973TH1F) have recalculated the phase shifts, including distortion of the deuteron cluster. This effect is important in the even-l cases. It leads to larger phase shifts than in calculations which do not include distortion, and in sharp resonance structure above 12 MeV. The pre '67 analyses were based on the analyses of differential cross section measurements; the newer ones also include the fitting of polarization measurements. On the basis of these analyses it is found that the d-wave shifts are split and exhibit resonance at Ex = 2.18 (3D3), 4.8 (3D2) and 5.7 MeV (3D1): the parameters of these states are displayed in Table 6.4 (in PDF or PS). A good fit to all data below Ed = 11 MeV is found with partial waves of l ≤ 3 (1972SC14). The p-wave phase shifts are small which is strong evidence against the existence of the T = 0 p-wave triplet reported earlier by (1964SE07): see (1967MC02, 1969KO1N, 1970KE17, 1972SC14). For Ed = 11.5 to 17 MeV, the vector analyzing power iT11 at a given angle is fairly constant (at θc.m. = 90° it is close to zero): this is also indicative of the absence of negative parity states in that region (1973CH35). At higher energies the l = 3 and 4 partial waves become important. The l = 0, 1 and 2 waves continue smoothly their low-energy behavior. [See, however, (1973TH1F)]. The interaction appears to be dominated by absorption (1967DA1B). See also (1969HA1Q, 1969KR14, 1969LI06).
In the range Eα = 30 to 80 MeV there is no difference in the cross sections for 2H(α, αp)n and 2H(α, αn)p, indicating that spin statistics play a dominant role in the deuteron breakup reactions and that charge and FSI effects are unimportant when quasi-free scattering conditions are satisfied (1972AL04). However, it is also found that the shapes of the quasi-free peaks do not remain the same for the two cases over the above energy range (1972AL1T). Reaction (b) appears to proceed at least partly via 6Li*(4.3) [whose Ex was assumed to be 4.57 MeV]. An upper limit for the T = 1 impurity amplitude of this state is estimated to be 10-2 (1972DE49). For other work on reaction (b), see (1968WA01, 1970AS02, 1970BO1Q, 1972HO1H, 1973CH05) and reactions 9 in 5He and in 5Li. See also (1965TO01, 1967FU1D).
See also (1967PL02, 1971AR1C), (1971HA2G), (1966RA1B, 1967HA1H, 1967LA22, 1967NA1E, 1968FI1E, 1968LA13, 1968PA1K, 1968TH02, 1969JA1J, 1969JA1G, 1969LI06, 1969NA09, 1969SC1K, 1969SH20, 1969TA1G, 1969TH1C, 1969VA1G, 1970AL1K, 1970CH1K, 1970HA1N, 1970HO32, 1970KU15, 1970NE1F, 1971KU22, 1971TE1B, 1972BL1F, 1972KU20, 1972NA1D, 1972RI10, 1973AU1K, 1973CH27, 1973NA12, 1973TH1E; theor.) and (1966LA04).
Angular distributions have been measured at E(3He) = 8 to 18 MeV (1967SP10; p0), 11 to 18 MeV (1967SP10; p1), 26 MeV (1965EC1A; p0, p1, p2), 28 MeV (1971KL1E; p0, p1, p2), Eα = 42 MeV (1970VI01; p0, p1) and 71.7 and 81.4 MeV (1973HA50: formation of 6Li*(0, 2.19, 3.56)). At Eα = 63.7, 71.7 and 81.4 MeV, the α spectra show that the sequential decay (reaction (b)) involves 6Li*(2.19) and possibly 5Li (1973HA50). See also (1961CH09, 1970BA1V) and 7Be.
The width, Γγ, of 6Li*(3.56) is 8.1 ± 0.5 eV. Γα,d for the forbidden decay of this state into α + d is < 1.3 eV (1969RA20). The measurements by (1968CR07) are incorrect: see the discussion in (1969RA20). (1973SA21) reports Γγ = 6.5+2.4-1.7 eV. See also Table 6.5 (in PDF or PS) and (1966LA04).
Measurements of reaction (a) with monochromatic γ-rays have been made for Eγ = 5.4 to 9.0 MeV (1964GR1A) and 10 to 32 MeV (1965BE1D). The cross section for reactions (a), (b) and (f) shows a possible peak at 6.75 MeV (1964GR1A), a maximum at ≈ 12 MeV (σ ≈ 1.6 mb) and a gentle decrease to 0.6 mb at 32 MeV (1965BE1D). Other maxima in the cross section for neutron production are reported in (1965BA16, 1965HA19, 1966CO1B, 1966PA12) and in (1966LA04). See also (1966HI1B, 1968OD1A).
The cross section for photoproton production (reaction (b)) is generally flat up to 90 MeV with a slight evidence of a hump at ≈ 16 MeV excitation (1970WO10). Additional peaks are reported by (1969SO13). The energy distribution of the photoprotons has been measured at Ebrem. = 95 to 102 MeV: the data are consistent with the predictions of the quasi deuteron model with a characteristic pair momentum parameter of 80 MeV/c (1968MA19). See also (1965BA16, 1965MA46, 1967DE12, 1973DE17, 1973GA16), (1973CO1N) and 5He.
The cross section for reaction (c) is ≲ 5 μb in the range Eγ = 2.6 to 17 MeV consistent with the expected inhibition of dipole absorption by isospin selection rules: see (1959AJ76, 1966LA04). See also (1965MA46) and (1973PA17).
The cross section for reaction (d) shows a peak at Eγ ≈ 21 MeV with σmax = 5.1 mb. The angular distribution of the tritons at that energy is asymmetric around 90°, indicating interference between E1 and E2 absorption (1968MU1A, 1970MU05). Between 19 and 35 MeV the cross section decreases from 0.46 ± 0.24 mb to 0.11 ± 0.06 mb (1968SH10). See also (1965BA16, 1965MA46, 1970WO10, 1973DE17), and (1966LA04). The cross sections reported in this reaction are not in agreement with those found in the inverse reaction: see reaction 1 and e.g. (1973VE09, 1973VE1B). For reaction (e) see (1968MU1A, 1970MU05, 1973DE17).
See also the review articles by (1966FU1C, 1967SH1E, 1968SC1B, 1973AR1L), (1965DA06, 1966SH06, 1969ME1D, 1972CR1E) and (1966FE1B, 1966KU12, 1967AU1C, 1967NE1C, 1968CO13, 1969CL1D, 1969MA1N, 1970KU02, 1971AU01, 1971GH1A, 1971GH1B, 1971MU19, 1972KU05, 1972WE03, 1973MA2C, 1973RA1G, 1973SH08, 1973SR1B; theor.).
Elastic scattering has been measured at Ee = 85 to 140 MeV (1966RA29), 200 to 499 MeV (1971LI10) and 200 to 600 MeV (1967SU1A). The elastic scattering shows a diffraction minimum at q2 = 8 fm-2. The diffraction feature in F2 indicates a lowering of the central charge density (1971LI10). A model-independent analysis of the scattering yields rrms = 2.51 ± 0.10 fm (1972BU01). See also (1967SU1A, 1969MO1J, 1971LI10, 1971NE03). Measurement of the ratio of elastic charge scattering from 6Li and from 7Li as a function of (momentum transfer)2 yields < r2 >1/26/< r2 >1/27 = 1.001 ± 0.008 (1971VA20).
The population of excited states of 6Li has been reported at Ee = 41 to 59 MeV (1969EI06: 6Li*(2.19, 3.56, 4.27, 5.37)), 63 to 128 MeV (1968HU03, 1968HU1C, 1969HU05: 6Li*(3.56)), 89 to 175.4 MeV (1971NE03: 6Li*(2.19, 3.56, 5.36)), 109.0 to 166.9 MeV (1969NE1B: 6Li*(3.56)), 109.0 to 281.7 MeV (1969NE1B: 6Li*(2.19)) and 200 and 499 MeV (1971LI10: 6Li*(2.19)). The inelastic electron groups are superposed on a rather large quasi-continuous background [see, e.g., (1969HU05)]. See also (1968EI03, 1970BR1E, 1972THZF, 1973TH1B, 1973YE1B). Table 6.5 (in PDF or PS) summarizes the results. See (1966LA04) for a summary of the earlier reported results.
Because of the astrophysical implications of a 0+ state in 6Be near the 3He + 3He binding energy, several attempts have been made to locate the analog state in 6Li at Ex ≈ 15.2 MeV. The results were negative: Γγ < 11 eV for the M1 width of the 0+ → 1+ transition to the ground state of 6Li (1973CA1M: Ee = 65 MeV; looked a Ex = 9.0 to 16.8 MeV), Γγ < 3 eV (1973FA04: Ee = 37, 50, 60 MeV), Γγ < 8.8 eV (1973BI1M: Ee = 100 MeV).
The harmonic oscillator parameters of the 1p and 1s shells in 6Li are qp = 50 ± 5 MeV/c and qs = 108 ± 9 MeV/c (1972AN27). For reaction (b) see also (1970WO10, 1971HE1K, 1973HE1L) and 5He. For reaction (c) see (1966AL1F, 1971HE1K, 1972GE1H, 1973HE1L, 1973JU1E). See also (1972TI03).
See also the reviews by (1966GO1C, 1968GO1J, 1972LO1L), (1970AN1G, 1971MO06) and (1966BO1B, 1966GR1D, 1966KU1B, 1966LO1F, 1966MA1F, 1967AL1D, 1967BO1E, 1967HA1J, 1967KA1A, 1967WO1B, 1968BO1N, 1968CI1D, 1968KU1B, 1969AL1E, 1969AU1A, 1969CH25, 1969CI1A, 1969GE08, 1969HA1N, 1969JA1H, 1969KU1C, 1969KU13, 1969MA1M, 1969NE1C, 1969SU1D, 1969VI02, 1970CH1M, 1970CI1B, 1970JA08, 1970JA21, 1970LA1D, 1970LO1J, 1970SP1C, 1970SU13, 1970VA15, 1971CH06, 1971CH23, 1971DE1T, 1971LO03, 1971LO07, 1971LO08, 1972BR20, 1972DR1B, 1972JE05, 1972KU20, 1973BA65, 1973DE18, 1973DO1H, 1973DO07, 1973EL1C, 1973HI03, 1973MA51, 1973RA04, 1973RA23, 1973WE18; theor.).
Angular distributions have been reported at En = 1.00 to 2.30 MeV (1967KN1A; n0), 4.8, 5.7, 7.5 MeV (1968HO03; n0), 10 MeV (1967CO01; n0, n1), 14.0 MeV (1966ME1C; n0, n1) and 14.2 MeV (1970AB04; n0, n1). See (1966LA04) for earlier references. The population of 6Li*(3.56) is weak: see (1966LA04, 1968HO03). See, however, (1966ME1C). See also (1971MI12; theor.) and 7Li.
Proton angular distributions have been measured recently at Ep = 3.6 to 9.4 MeV (1967HA07, 1967HA08; p1), 4.3 to 9.4 MeV (1967HA07, 1967HA08; p2), 14.0 MeV (1968ME25; p0, p1, p2), 24.4 MeV (1968AU05, 1968AU06; p2), 25.9, 29.9, 35.0, 40.1, 45.4 MeV (1972BR20; p0, p1), 25.9, 45.4 MeV (1972BR20; p2), 33.6 MeV (1970KU1D; p0), 49.8 MeV (1971MA13, 1971MA44; p0, p1), 100 MeV (1968LI1C; p0), 144 MeV (1972JA07; p0), 152 MeV (1966RO1C; p0), 155 MeV (1968GE04; p0), 155 MeV (1965JA1A: 6Li*(2.2 ± 0.05, 3.6 ± 0.1, 4.5, 5.5)), 185 MeV (1970HU13; p0, p1, p2) and 600 MeV (1973GA1M; p0). See also (1971KO1G). See (1966LA04) for a listing of the earlier references.
Inelastic groups corresponding to excited states of 6Li are displayed in Table 6.6 (in PDF or PS): no others appear for Ex < 16 MeV (1968MA02). See also (1969KO1M, 1970BA1V) and (1968GL1A, 1968NE1B, 1969MA1G, 1969NE1A, 1969TI02, 1969WA11, 1973RA04; theor.).
Angular correlations of protons (reaction (b)) corresponding to 5He(0) show an l = 1 character, but with an anomalously low peak-to-valley ratio, as compared e.g. with 7Li, suggesting a significant s-wave contribution (1967RO06: Ep = 156 MeV); and see discussion in (1972MA61) relating both to this transition and to the one involving 5He*(16.8). See also (1965BE1E, 1970TH1F, 1972MI1N, 1973MI1J, 1973CO2B), (1966LA04) and (1966JA1A, 1967JA1C, 1967JA1D, 1967JA1E, 1968KU1B, 1968SA1C, 1968TA1K, 1969JA1D, 1969KO1J, 1972KO1L, 1973BA65, 1973CH1Q; theor.)
Reaction (c) has been studied at Ep = 9 and 10 MeV (1968VA02), 19 MeV (1971LI1N, 1973LI22), 45 MeV (1970BR1N), 56.5 and 61.5 MeV (1969RO04, 1970JA17), 100 MeV (1971MA61, 1973GO2A), 118.1 MeV (1972BA2L), 156 MeV (1968BA09, 1973BA01), 590 MeV (1972AL21, 1973KI1M) and 1 GeV (1967SU1C). At Ep = 590 MeV, in a kinematically complete experiment, the width of the momentum distribution of a deuteron in 6Li is found to be 124 ± 4 MeV/c (1972AL21) [see also preliminary report by (1973KI1M)], while (1970JA17) find 70 ± 8 MeV/c at Ep = 56.5 MeV. See also (1973CH1R). The probability for a deuteron cluster in 6Li is estimated to be 0.45 ± 0.08 (1971MA61), 0.13 ± 0.05 (1973LI22). At Ep = 9 and 10 MeV sequential decay via 6Li*(0, 2.19, 4.6, 6.0) dominates the yield: the final state interactions do not support the previously proposed [see (1966LA04)] negative-parity states in 6Li (1968VA02). See also (1966SE1C, 1971GA1J, 1973CO2B), (1968KO1E) and (1965NE1B, 1966ZE1A, 1968RO1F, 1969BO1G, 1969HO1K, 1969JA13, 1969NA1H, 1970JA1L, 1970MI1J, 1973RO2B; theor.). See also reaction 9 in 7Li (1973WE07).
Angular correlation studies in reaction (d) give evidence for an appreciable 3He + 3H configuration in 6Li(0) (1968BA09, 1970BA1T, 1973GO2A). At Ep = 590 MeV, in a kinematically complete experiment, the width of the momentum distribution is determined to be 168 ± 34 MeV/c (1973DO12). See also (1969KO1G, 1973RA1G) and 7Be. For reaction (e) see (1972MI1N, 1973MI1J). For reaction (f) see (1973CO2B).
Angular distributions of deuterons have been measured at Ed = 4.5 to 5.5 MeV (1970PO03; d0), 8 to 12 MeV (1970BI1B, 1971BI11; d0), 11.8 MeV (1968LU02; d0, d1), 14.7 MeV (1969MA13; d0, d1) and 19.6 MeV (1971CHYH; d0). The T = 1, 0+ state, 6Li*(3.56), is not appreciably populated. See also (1966LA04) and (1966BR1G). 6Li*(4.31) has been studied at Ed = 20 and 25 MeV: a single-level, many-channel fit yields Γ = 1.82 ± 0.11 MeV (1975BR21). See also (1968LE15). See Table 6.6 (in PDF or PS) for a summary of the results on excited states.
At Ed = 21 MeV reaction (b) shows spectral peaking (characteristic of 1S0 for the pn system [T = 1]) when 6Li*(3.56) is formed, in contrast with the much broader shape (characteristic of 3S1) seen when 6Li*(0, 2.19) are populated (1972BR03). See also (1973CH05). A study of reaction (c) at Ed = 52 MeV shows that the α-clustering probability, Neff = 0.12+0.12-0.06 if a Hankel function is used (1973HA31) [see this reference also for a discussion of other results on momentum distributions and α-clustering probability in 6Li]. The α-particle and the deuteron clusters in 6Li have essentially a relative orbital momentum of l = 0. The D-state probability of the ground state of 6Li is ≈ 5% of the S-state (1973HA31). Quasi-free scattering is an important process even for Ed = 6 to 11 MeV (1973MI20). Interference effects are evident in reaction (c) proceeding through 6Li*(2.19, 4.31): this is due to the experiment being unable to determine whether the detected particle was emitted first or second in the sequential decay (1968LE15). See also (1973JA21). For reactions (d) and (e) see (1968LE15) and (1974GR02).
Angular distributions have been measured at E(3He) = 8 to 20 MeV (1968LU02: g.s.), 21, 24 and 27 MeV (1966VA1B, 1967BL1E: g.s., 2.19), 24.6 and 27 MeV (1971GI1E, 1972GI07: g.s., 2.19, 3.56), 34 MeV (1971CHYH: g.s.) and 217 MeV (1973WI07: g.s.). At E(3He) = 24.0 MeV the population of 6Li*(0, 2.19, 3.56, 4.53, 5.37) is reported by (1973VE1B). See also (1967CO1J) and (1973DU1D; theor.).
Angular distributions (reaction (a)) have been measured at Eα = 3.0 and 4.0 MeV (1972BO07; α0), 12.54 to 18.54 MeV (1970BI1B, 1971BI12; α0), 25 MeV (1969DO1H; α0, α1), 29.4 MeV (1968MA25, 1969MA13; α0, α1), 36.5 MeV (1971CHYH; α0), 104 MeV (1968HA1D, 1969HA14, 1970HA1G; α0) and 166 MeV (1972BA89; α0). See (1966LA04) for earlier references. In the range Eα = 12.5 to 18.5 MeV the optical model gives good agreement with the elastic angular distributions when a target spin-orbit potential is included (1971BI12). At Eα = 104 MeV the elastic angular distribution shows a pronounced diffraction pattern (1969HA14) while at 166 MeV there is some backward peaking in addition to a single strong forward peak (1972BA89). See also (1969TR1B, 1970FO1B, 1970MI1J, 1973CL1K; theor.) and (1969HO1K).
Reaction (b) has been studied by (1969PU01, 1970WA1U, 1971WA19) at Eα = 50.4, 59.0, 60.5, 70.3 and 79.6 MeV. At each of these energies several coincident energy spectra of the two α-particles were taken, with special emphasis on those angles at which zero lab momentum is possible for the residual deuteron. From the measurements at these particular angles, off-mass-shell α - α cross sections were extracted and were found to be in excellent agreement with the free α - α cross sections at comparable energies: see 8Be. The momentum distribution for α-particles in 6Li has a width of 29 ± 2 MeV/c. The effective number of α + d clusters for 6Li(0), Neff = 0.08 ± 0.04. The knockout process appears to occur only in the nuclear surface region (1971WA19).
Reaction (b) has also been studied at Eα = 23.6 MeV (1969BA18), 25 MeV (1969DO02, 1969DO1H), 29.4 MeV (1968MA25), 37.5 and 43.5 MeV (1971DE15), 42.8 MeV (1970GA14), 55 MeV (1968PI04, 1969PI11, 1970PI1D), 64.3 MeV (1970JA17). See also (1967MO1F, 1969VE1B, 1973JA21, 1974DO1G). The reaction 6Li(α, αx)Y has been studied at Eα = 50 MeV [x = p, d, t, 3He, α]: p, d, and α clustering is strong, t and 3He clustering is weak (1971LA20). See also (1968BA1H, 1969DO03, 1970BU1C, 1970MI12, 1972KO1J, 1972AV04; theor.).
Angular distributions of elastically scattered 6Li ions have been measured at E(6Li) = 3.2 to 7.0 MeV (1966PI02), 8 to 14.5 MeV (1973GR34), 12, 20 and 28 MeV (1971FO08), 30 MeV (1971DA33), 32.0 MeV (1970NA02: also 6Li*(3.56)), and 32.0 and 36.0 MeV (1973WH02: for both 6Li*(3.56)). A microscopic DWBA analysis (including the tensor interaction and exchange) gives good agreement with the data (except at forward angles) and with the cross sections for this reaction and for the reaction to the analog ground states of 6He and 6Be (1973WH02). See also reaction 9 in 6He. (1971FO08) report that the reaction mechanism is dominated by absorption. See also 12C in (1975AJ02) and (1972CL14, 1973PE13; theor.).
At E(16O) = 36 MeV the elastic angular distribution has been measured by (1971OR02).
Angular distributions of deuterons (reaction (a)) have been recently studied at Ep = 30.3 MeV (1969DE04: 6Li*(0, 2.19, 3.56)), 33.6 MeV (1967KU10, 1970KU1D: 6Li*(0, 2.19, 3.56, 5.37)), 100 MeV (1968LE01, 1969LI02: 6Li*(0, 2.19, 3.56, 5.6)) and 155.6 MeV (1968BE72, 1969BA05, 1969TO1A: 6Li*(0, 2.2 ± 0.08, 3.6 ± 0.1, 4.5 ± 0.15, 5.5 ± 0.1)). No states other than those reported above have been observed up to Ex = 18 MeV (1967KU10), 20 MeV (1969BA05). See also (1966LA04) and (1970BA1V, 1972AZ03). At Ep = 12 MeV (1969CO06) have studied the ratio of the cross section of the (p, d) reaction to that for the (p, d) reaction, in which singlet deuterons are formed: σ(p, d)/σ(p, d) = 41.0.
The angular distributions of the tritons to 6Li*(0, 2.19, 3.56) at Ed ≈ 15 MeV indicate ln = 1, and therefore even parity, for the first three states of 6Li: see (1966LA04). A careful study at Ed = 10 - 12 MeV, in a region in 9Be which is free of sharp resonances, shows that the t0 angular distributions which have both fore and aft maxima can be reproduced using a multi-interaction, exact finite-range two-mode DWBA formalism (1970ZE1C, 1971ZA07, 1973WE09).
A study at Ed = 23.6 MeV of the relative cross sections of the analog reactions 7Li(d, t)6Li (to the first two T = 1 states at 3.56 and 5.37 MeV) and 7Li(d, 3He)6He (to the ground and 1.80 MeV excited state) shows that 6Li*(3.56, 5.37) have high isospin purity (α2 < 0.008): this is explained in terms of antisymmetrization effects which prevent mixing with nearby T = 0 states (1971DE08). See also (1970BA1V) and (1971WE1L, 1973DU1D; theor.).
Angular distributions have been reported at E(3He) = 5.1 to 12 MeV (1969LI06; α1), 5.1 and 7.5 MeV (1969LI06; α2), 5.5 to 9.0 MeV (1969LI06; α0), 6.0 and 7.5 MeV (1970OR03; α0, α1, α2), 8.7 MeV (1969MA1J; α1), 8.7 and 9.7 MeV (1969MA1J; α0), 16 to 18 MeV (1970ZE1C, 1971ZA07; α0) and 21, 24 and 27 MeV (1966VA1B, 1967BL1E; α0, α1, α2). See also (1969OR01) and 10B. At E(3He) = 16 to 18 MeV, in a region where there are no sharp or strong resonances in the compound nucleus, both the forward and the backward maxima in the α0 angular distributions are reproduced by conventional DWBA without inclusion of exchange terms. However, the cross section derived from zero range DWBA is a factor of 25 smaller than the observed cross section. For finite range analysis no appreciable renormalization is necessary (1971ZA07). See also (1973WE1V; theor.).
At E(3He) = 3.8 to 5 MeV, α groups are observed to the ground state and to excited states at Ex = 2.17 ± 0.02, 3.55 ± 0.02 and 5.34 ± 0.02 MeV [Γ = 560 ± 40 keV]: no evidence is seen for other excited states below Ex = 10 MeV previously reported by (1960AL10), even after a spectrum was taken at the energy [E(3He) = 0.9 MeV] at which the earlier work was done (1968CO07). (1969LI06) observe states at Ex = 2.179 ± 0.008, 3.568 ± 0.008 and 5.36 ± 0.03 MeV [Γ ≈ 0.54 ± 0.04 MeV].
At E(3He) = 11 to 12 MeV only structureless broad spectra are observed in the region 15.6 ≤ Ex ≤ 16 MeV: there is no evidence for a sharp T = 1 analog of a state in 6Be near the 3He + 3He binding energy postulated for astrophysical considerations (1972MA1W).
Several attempts have been made to look at the isospin decay of 6Li*(5.37) [Jπ = 2+; T = 1] via 7Li(3He, α)6Li* → d + α: the branching is < 2% (1971CO22), < 1% (1973BR20). If Γ(5.37) = 560 keV [see above] Γd ≤ 12 keV and θ2d(5.37) ≤ 0.5% (1971CO22). See, however, (1973BR20). Γp/Γ = 0.35 ± 0.10 and Γp+n/Γ = 0.65 ± 0.10 for 6Li*(5.37) (1973AR05). See also (1970KA1M, 1972AR1C, 1972KA08) and (1966LA04).
Angular distributions of α-particles (reaction (a)) have been measured at Ep = 0.11 to 0.60 MeV (1973SI27; α0), 0.3 to 0.9 MeV (1968BE1N; α0), 6 to 11.5 MeV (1963BL20; α0, α1), 5.9 and 7 MeV (1964YA1A; α0, α1), 15.6 and 18.6 MeV (1962MA40; α0, α1), 26.7 and 38 MeV (1967AC01, 1969GA03, 1970GU06; α0, α1) and 45 MeV (1970DE17, 1971DE2B, 1971PE10, 1972DE01, 1972DE02; α0, α1, α2 and 6Li*(0, 3.56)). At Ep = 45 MeV the reaction appears to proceed by a direct process, with a rise at back angles attributed to a pickup process. The 3.56 MeV state decays by γ-emission: Eγ = 3.572 ± 0.012 MeV; the internal pair spectrum is consistent with an M1 transition (1954MA26). The α-decay of 6Li*(3.56) is forbidden by spin and parity conservation: Γα/Γ is measured to be < 0.025 (1972AR1C). See also (1972KO1N). For the decay of 6Li*(5.37) see reaction 22 (1973AR05). See also (1966DO1A, 1966LA20, 1970MA1K) and (1969TH1D, 1973ED02; theor.). See also 10B and (1966LA04).
At Ep = 9 MeV, the yield of reaction (b) is dominated by final state interactions through 8Be*(0, 2.9) and 6Li*(2.19) with little or no yield from a direct three-body decay (1971EM01). See also (1967FI1D).
Not reported: see (1964BL1C).
Angular distributions of 6Heg.s. + 6Lig.s., 6Lig.s. + 6Heg.s., 6Li*3.56 + 6Heg.s., and 6Heg.s. + 6Li*3.56 [the second listed ion being the detected one] have been measured at Et = 23.5 MeV. In the latter two cases the final state is composed of two isobaric analog states: angular distributions are symmetric about 90°c.m., within the overall experimental errors. In the reaction leading to the ground states of 6He and 6Li differences from symmetry of as much as 40% are observed at forward angles.
Angular distributions involving 6Heg.s. + 6Li*(2.19) and 6Lig.s. + 6He*(1.8) have also been measured (1973VO08).
Angular distributions of the 6Li ions have been obtained at E(3He) = 6, 7, 8 and 10 MeV (1969TA05) and 7.0 and 9.0 MeV (1972YO02): these and the fairly smooth yield curves for E(3He) = 6 to 9 MeV [see 12C in (1975AJ02)] seem to suggest that the mechanism of the reaction is essentially direct. The triton spectroscopic factors in 9Be are determined to be 0.073 and 0.052 at 7 and 9 MeV, respectively (1972YO02). See also (1971ZE03; theor.).
For reactions (a) and (b), see reactions 23 and 28 in 10B. For reaction (c) see (1970NA06). Reaction (d) has been studied at Eα = 28.4 MeV (1967TA1C). Reaction (e) has been studied at Eα = 46 MeV (1970ZE03). See also (1966GE12) and 10B.
At Ed = 19.5 MeV angular distributions have been measured for the 6Li ions to 6Li*(0, 2.19). The experimental cross sections of the ground state transition are two orders of magnitude greater than those predicted by the shell model, consistent with the cluster nature of 6Li (1971GU07). See also (1972GA1E).
Angular distributions of 6Li ions are reported at Ed = 19.5 MeV for transitions to 7Li*(0, 0.48) (1971GU07). At Ed = 40 MeV the cross section for the transition to 6Li*(3.56) is half the cross section for the reaction 11B(d, 7Be)6He to the analog state (the ground state of 6He) [to within 10%] as predicted by isospin conservation (1972GO1P).
Angular distributions of 6Li ions are reported at E(3He) = 3.0 and 5.2 MeV. The reaction has been observed to lead to 8Be*(2.9) + 6Li(0) and to 8Be(0) + 6Li*(3.56). It is suggested that 6Li*(3.56) contains a far smaller admixture of the (3He + t) configuration than does 6Li(0) (1964YO06, 1967YO02). See also (1967YO1C).
Angular distributions of the 6Li ions corresponding to the transition to 7Be*(0 + 0.43) have been measured at five energies in the range Ep = 36.0 to 56.8 MeV and the data have been analyzed using zero-range and finite-range DWBA assuming the pickup of 5He and 6Li clusters as the dominant mechanism. The differential cross sections decrease with energy: at Ep = 36 MeV, dσ/dΩ as large as 200 μb/sr are observed (1971HO1K, 1971HO25). The angular distribution has also been measured at Ep = 45 MeV by (1971BR07).
Angular distributions have been obtained of 6Li and 10B ions corresponding to transitions to 6Li*(0, 2.19) and 10B*(0, 0.72, 2.15) (1972RU03: Eα = 42 MeV).
At Ep = 45 MeV, the angular distributions of the 6Li ions corresponding to the transitions to 8Be*(0, 2.9) have been measured: the cross sections, integrated from 20° to 85° c.m., are, respectively, 1.9 and 2.7 μb (1971BR07).
Angular distributions have been obtained of 6Li and 14N ions corresponding to the population of the ground states (1972RU03: Eα = 42 MeV).
Angular distributions have been measured at E(3He) = 11 MeV (1971ST06: 6Lig.s. + 16Og.s., 6Lig.s. + 16O6.06+6.14, 6Li3.56 + 16Og.s.), 22.4, 30.0 and 40.7 MeV (1972OH01: 6Lig.s. + 16Og.s. except at 30.0 MeV where also 6Li3.56 + 16Og.s.) and at 28 MeV (1970KL09: 6Lig.s.+16Og.s., 6Li3.56 + 16Og.s.). The angular distributions involving 16Og.s. show pronounced diffraction structure. The direct-reaction mechanism appears to involve coupling 3He and t with l = 0 angular momentum to either a singlet or triplet state (1970KL09). The ratio σg.s./σ3.56 = 2.24 ± 0.07 rather than 3 (from the ratios of 2J + 1) but this is accounted for by the Q-value dependence of the cross sections (1970KL09). See also 16O in (1971AJ02).